feat(runtime): unregister service revisions

Add a lifecycle-serialized unregister operation that stops a resident Actor before releasing its registered and compiled Component.

Return the existing not-registered and unavailable errors without leaving a partially removed live revision, and cover Actor and registration count cleanup.

crates/wasmeld-runtime/src/runtime.rs

@@ -390,6 +390,55 @@ impl Runtime {
         self.start(&key, init_config)
     }
 
+    /// Stops and removes one registered service revision.
+    ///
+    /// Callers must switch any external deployment reference away from this
+    /// revision before unregistering it.
+    pub fn unregister(&self, key: &ServiceKey) -> Result<(), RuntimeError> {
+        let _lifecycle = self
+            .inner
+            .lifecycle
+            .lock()
+            .map_err(|_| RuntimeError::LockPoisoned)?;
+
+        if !self
+            .inner
+            .services
+            .lock()
+            .map_err(|_| RuntimeError::LockPoisoned)?
+            .contains_key(key)
+        {
+            return Err(RuntimeError::ServiceNotRegistered(key.clone()));
+        }
+
+        let actor = self
+            .inner
+            .actors
+            .lock()
+            .map_err(|_| RuntimeError::LockPoisoned)?
+            .get(key)
+            .cloned();
+        if let Some(actor) = actor {
+            if actor.is_available() {
+                actor.stop()?;
+            } else if actor.is_alive() {
+                return Err(RuntimeError::ActorUnavailable(key.clone()));
+            }
+            self.inner
+                .actors
+                .lock()
+                .map_err(|_| RuntimeError::LockPoisoned)?
+                .remove(key);
+        }
+
+        self.inner
+            .services
+            .lock()
+            .map_err(|_| RuntimeError::LockPoisoned)?
+            .remove(key);
+        Ok(())
+    }
+
     /// Returns counts without exposing internal Engine or Store state.
     pub fn stats(&self) -> Result<RuntimeStats, RuntimeError> {
         let registered_services = self

crates/wasmeld-runtime/tests/runtime_components.rs

@@ -283,6 +283,23 @@ fn kv_capability_requires_a_backend_and_enforces_limits() {
     runtime.stop(&key).unwrap();
 }
 
+#[test]
+fn unregister_stops_actor_and_releases_compiled_revision() {
+    let runtime = Runtime::new(RuntimeConfig::default()).expect("runtime should start");
+    let key = register_component(&runtime, "unregister", "echo_component.wasm", test_limits());
+    runtime.start(&key, Vec::new()).unwrap();
+
+    runtime.unregister(&key).unwrap();
+
+    let stats = runtime.stats().unwrap();
+    assert_eq!(stats.registered_services, 0);
+    assert_eq!(stats.running_actors, 0);
+    assert!(matches!(
+        runtime.start(&key, Vec::new()),
+        Err(RuntimeError::ServiceNotRegistered(missing)) if missing == key
+    ));
+}
+
 #[test]
 fn registration_rejects_non_whitelisted_wasi_imports() {
     let runtime = Runtime::new(RuntimeConfig::default()).expect("runtime should start");